mercurial/interfaces/util.py

typing: make `bundlerepository` subclass `localrepository` while type checking

Currently, `mercurial/bundlerepo.py` is excluded from pytype, mostly because it
complains that various `ui` and `vfs` fields in `localrepository` are missing.
(`bundlerepository` dynamically subclasses `localrepository` when it is
instantiated, so it works at runtime.)  This makes that class hierarchy known to
pytype.

Having a protocol for `Repository` is probably the right thing to do, but that
will be a lot of work and this still reflects the class at runtime.  Subclassing
also has the benefit of making sure any method overrides have a matching
signature, so maybe this is a situation where we do both of these things.  (I'm
not sure how clear the diagnostics are if a class *almost* implements a
protocol, but is missing a method argument or similar.)  The subclassing is not
done outside of type checking runs to avoid any side effects on already complex
code.

# util.py - Utilities for declaring interfaces.
#
# Copyright 2018 Gregory Szorc <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

# zope.interface imposes a run-time cost due to module import overhead and
# bookkeeping for declaring interfaces. So, we use stubs for various
# zope.interface primitives unless instructed otherwise.

from __future__ import annotations

from .. import encoding

if encoding.environ.get(b'HGREALINTERFACES'):
    from ..thirdparty.zope import interface as zi

    Attribute = zi.Attribute
    Interface = zi.Interface
    implementer = zi.implementer
else:

    class Attribute:
        def __init__(self, __name__, __doc__=b''):
            pass

    class Interface:
        def __init__(
            self, name, bases=(), attrs=None, __doc__=None, __module__=None
        ):
            pass

    def implementer(*ifaces):
        def wrapper(cls):
            return cls

        return wrapper